Zinc distillation.



J. U. MOUL & H. W. WEBSTER. ZI STILLATION. APPLICATION FILED DEC. 29,1910.

Patented June 25, 1912.

to those; ores of zinc. which contain" sensible UN TED sTAirEs PATENTOFFICE.

JOHN COLLET'IIMOULDEN AND HAROLD WOLSTAN WEBSTER. or "sm'roN cAnEwQENGLAND, assreNoa's TO CENTRAL ZINC ooMrANY LIMITED, or sne'roN-"cannw,

ENGLAND.

ZINC. Drs'rILLA'rIoN.

Patented June 25, 1912.

Application filed December 29, 1910. Serial 1V0. 599,832. I

*useful Improvements in Zinc Distillation,

of which the following is a specification.

This invention is for improvements in or relatin to zinc distillation,the object beingto ten er the distillation more efficient andparticularly to increase the amount of spelter formed and to avoid the;formation of zinc oxid-.- v y The invention is particularly. applicableproportions of lead: and silver and the residues of'which havetobetreated after distillation for the recovery of their lead and silvercontents. V i v Y The, ores to be treated according to the presentmethod must be oxidized ores, either as vfound in nature or otherwiseoxidized.

.In the. distillation of zinc this invention consists in bringing intocontact with the" retort vapors a haloid salt such as sodium chloridwhich in the presence of carbon monoxid tends to. prevent the formationof [More particularly in the distillation of zinc from products whichcontain other metals such as lead and silver this inventionconsists' inplacing a haloid salt. such 'as' sodium chlorid in the path of the 2retort vapors i. e. in the vfront of the retort. or in the back of-thecondenser to diminish the production of zinc'oxid and to increase theproduction of-metallio zinc.

Hitherto it-has been proposed in'the distillation of certain zinc oresto mix common salt with the retortchargewiththe object of improving thedistillation. It is found however-that the salt has no beneficial effectin the actual decomposition of the orebut on the other hand the presenceof salt in the charge is detrimental where the ore contains metals otherthan zinc (such as lead and silver) because the presence of the saltresultsin a chloridizing roast by which metals other than zinc aredriven off 'in the form of volatile chlorids, thereby contaminating thezinc products and depleting the residues.

According to this invention the haloidsalt such as sodium chlorid is notmixed with the retort charge but is so placed that containing say twocwt-s. of a mixed charge containing anore comprising compounds ofzinc'with some lead and silver, about 4 .ozs. of salt are placed. in themouth of the retort in order to separate the. salt from the retortcharge, alayer of coke breeze may be introduced into the mouth ofthe-retort be fore the salt. Alternatively,the small quantity. of saltmay be placed at theback of thecondenser, and this invention includesthe provision of a small pocket or receptacle for salt at the-back ofthe condenser and above .thelevel of ,the'condensed zinc. As the hot.

vapors'from the retort pass over the salt,

.the vapor from the salt comes in. Contact with the vapors. and thetendency. is to prevent the formation of zinc oxid and to increase theyield of spelter. a

Several advantages accrue from the invention. .In th'e first place thequantity of 'spelter obtained from each retort charge is materiallyincreased, and from the investigations made up to the present it appearsthat any lead carried over with the-zinc readily settles out therefrom.The production of blue powder is diminished and the condensation istherefore better: and

.' owing to the decrease of ox'id fumes the furnace-main can more easilyinspect the progressofdistillation. In cases where the fumesffrom thec'ondenserpass through a nozzle thefiam'e'is bright yellow and forms auseful source of illumination. The zinc products are found to becomparatively 'free of contamination.

Thetheoretical reasonsTfor the advantageous results are not positivelydeterk mined, but this invention would include the employment of anycatalytic agent (such as other metallic chlorids) which in the presenceof carbon monoxid will prevent the formation of zinc oxid.

This invention is applicable to" the distillation of zinc by any knownmeans, electrical or otherwise. I i

The figure shows a form of apparatus for carrying this invention into.effect.

A is the retort into which the charge of zinc ore and carbonaceousmaterial is inserted. The retort Ahas an opening B into which fits acondenser C, and is preferably arranged so that it has a slope as hasalso the condenser. The condenser C is provided with a pocket I)preferably of a shallow cup form, at a point nearthe opening intotheretort, and is also provided with an outlet E for thegases from theretort and an outlet F from which the zinc is run off. .The charge isintroduced into the retort I and the condenser is placed in positionwith tit of'haloid salt G, as for example sodium its end in the openingB of the retort. A layer of coke breeze may be introduced into the mouthof the retort. The joint of the condenser with the retort is packed withclay or other suitable material as is also the outlet F from which themolten .zin'c is run oif. Into the pocket D is placeda small quanchorid. The retort is heated and the zinc vapors distil and pass into thecondenserv thereby heating the salt in the cup D and causin it'to give:off vapors. The vapors mix wlth the zinc vapor and enable them to ofzinc distillation which consists in bring-;

condense in the lower endof the condenser without formation of zinc oxidand blue owder When suflicient zinc is condensed t e plug of clay isremoved from the openin F and the zinc is run 01]., another plug beingplaced in position to seal the condenser for a further time. The fumesfrom the retort pass through the condenser and out of thenozzle E.

' What we claim as our invention and desire to secure byLettersPatent-isz- 1. The herein describedstep in the process.

'Ofzinc distillation which consists. ing into contact with retort vs "rsa halo d salt to revent the formation 0 zinc oxid.

' 2. T e hereimdescribed step inthe process ing into contact with retortva rs common salt to prevent theforma-tion o zinc oxid.

3. The herein-described process for the" production of, substantiallypure oxidizedi-oref which consists in heating the oxidized "ore with areducing agent to 'generate zinc vapor therefrom, bringing the vaporinto cont-act with a haloid salt to pre- .vent the formationof zineoxid,and-: condens= ing metallic zinc.

- 4. The herein-described processfor the .sists in placing common saltat the front of I 65 '1 g 7. The herein-described step in the processproduction of substantially pure -rinc from oxidized ore which consistsin heating the oxidized ore with a reducing agent to generate zinc vaportherefrom, bringing the vapor into contact with common salt to preventthe formation of zinc oxid, and condensing metallic zinc.

5. The hereindes'cribed step in the process of zinc distillation fromretorts which'conslsts in placing common salt in the pathof the-retortvapors for the purpose'described.

6. The herein-describedstep in the process of zinc distillation fromretorts which conthe retort for the purpose described.

of zinc distillation from retorts which consists n placing common saltin the condenser at the back thereof and above the levelof 9. The ethodof treating complex oxi- 'dized ores containing zinc and other metalsfor the'recovery of metallic. zinc substantiall; free from zinc oxid,which consists in mixing the ore with a reducing agent, heatingthe.mixture to generate therefrom a va 1' of nine mixed with carbonmonoxid, nging a vapor of common salt into con tact with the zin vaporto prevent the for.-

tallic zinc. v

Intestimony whereof we have signed our names to this specification inthepresence of two subscribing witnesses. I JOHN COLLETT MOULDEN. HAROLDWOLSTAN WEBSTER.

Witnesses-z. Y

J no. I. DAVIES, E. W. WARING.

mation of zinc oxid, and condensing me-

